Alarm or signal sending system



Aug. 20, 1935.

R. M. HOPKINS ALARM OR SIGNAL SENDiNG SYSTEM Filed Jan. 5;, 1950 4Sheets-Sheet l IAAA l INVENTOR fiicizard MHop%zns ATTORNEY "I r I 20,1935. R. M. HOPKINS 3 ALARM OR SIGNAL SENDING SYSTEM Filed Jan. 3, 19504 Sheets-Sheet 3 my. 21 my};

y i fi 14 144 3 7 t/ E I 6% 6142 O INVENTOR IATTQORINEY Aug. 2@, 135. R.M. HOPKINS ALARM OR SIGNAL SENDING SYSTEM Filed Jan. 3, 1930 4Sheets-Sheet 4 ATTORNEY Patented Aug. 20, 1935 UNlTED STATES PET OFFICEALARM on SIGNAL SENDING SYSTEM Application January 3, 1930, Serial No.418,328

18 Claims.

. on the premises, though it is noted that the invention is not limitedto features of the system as a whole but includes also features of thetransmitter and pull stations.

One object of the invention is to provide an improved system of thiskind having a single transmitter controlled by a plurality ofinexpensive pull stations at various locations and connected to thetransmitter by local circuits.

Another object of the invention is to provide a system of this kindwhich will operate with a break in one of the main lines and which willautomatically send a signal should a break occur in a local circuit,while maintaining the local cir cuit operative for sending an alarm.

Another object of the invention is to provide an improved pull stationfor a system of this kind and an improved transmitter which will send awinding signal and other kinds of signals from a single winding.

Other objects of the invention are to improve generally the simplicityand efficiency of such systems and apparatus and to provide a system orapparatus of the kind stated which will be economical, durable andreliable in operation, and economical to manufacture and install.

Still other objects of the invention will appear as the descriptionproceeds; and while herein details of the invention are described andclaimed, the invention is not limited to these, since many and variouschanges may be made without departing from the scope of the invention asclaimed in the broader claims.

The inventive features for the accomplishment of these and other objectsare shown herein in connection with an improved alarm system which,briefly stated, includes a transmitter interposed between the pair ofmain line wires and including normally shunted electromagnets and asignalwheel-operated switch interposed in the circuit, said transmitterincluding means whereby a short trouble signal is sent if one magnet isenergized and a long alarm signal is sent when both have been energized.

A pair of local shunt circuits both passing through a series of pullstations normally short circuit and deenergize the magnets respectively,whereby it a break occurs in either local circuit one of the magnetswill be energized and not shunted, thus causing a short trouble signal.

A lever operated switch assembly in each pull station is operable tobreak both shunts, thereby to send a long alarm signal.

In the accompanying drawings showing, by way of example, one of manypossible embodiments of the invention,

Fig. l is a simplified diagram showing the circuits of the completesystem;

Fig. 2 is a less simplified a less diagrammatic diagram showing thecircuits of the transmitter, pull stations and central ofiice;

Fig. 3 is a front elevation showing the transmitter and its housing;

Fig. 4. is a side elevation showing mitter clockwise;

Fig. 5 is a rear elevation of the clockwork;

Fig. 6 is an elevation, partly in section, showing the details of thetransmitter control means;

Fig. 7 is a fragmental front elevation showing the rear pillar plate ofthe clockwork and parts of the transmitter control means in anotherposition;

Fig. 8 is a side elevation of one of the tripping cams;

Figs. 9 to 12 are rear elevations showing different positions of thepull switch;

Fig. 13 is a front elevation of a pull box showing the lever compartmentopen;

Fig. 14 is a front elevation of a pull box showing the switchcompartment open; and

Fig. 15 is a front elevation showing a group of all of the apparatus asexposed in use.

The herein signalling system may be used in connection with any usual ordesired suitable arrangement of central oflice, such for instance asthat shown very diagrammatically in Fig. 1 wherein a pair of main linewires 10 and II terminate in the central ofiice in a pair of groundedlegs l2 and 13 respectively.

Recording receivers I l and I5 have relays l6 and il in said line wiresrespectively.

A generator 20 is interposed in one of the grounded legs l3 between thereceiver and the ground.

A switch 21, used in case of a break in one of the main line wires, isprovided, whereby both of said lines Ill and H may be connected to oneterminal. 22 of the generator, only the other terminal 23 remaininggrounded, the relay It being ungrounded, thereby to send current of thesame sign into both ends of the main line, the circuit to be completedthrough the grounds at the local stations only during operation of thetransmitting or pull stations as will be explained.

A normally closed signal circuit is shown inthe transeluding said pairof main line wires and one or a plurality of transmitters 25 interposedtherein.

The main features of the system will first be very briefly described;and then the parts will be described in detail.

The system as a whole The transmitter includes a pair of normallyshunted and de-energized electromagnets 88, SI and asignal-wheel-operated normally closed signal switch I69, lBI, H32, theswitch and magnet coils being adapted to be interposed in series in saidcircuit between said main line wires I and II.

The transmitter 25 includes mechanism, which will be fully described,whereby a short winding signal is automatically sent whenever thetransmitter is completely wound up, and means whereby an additionalshort trouble signal is sent if only one magnet 85 or 8| is energizedand a long alarm signal is sent when both magnets have been energized.

The signal initiating system includes a normally closed testing ortrouble switch I 4 I I42 having one member I 4| connected to a part I50of the main circuit between said magnets, and a double-shunt localcircuit comprising a pair of associated local shunt circuits I04, I04,I65, I 05', I05, I06, I91, I01 connecting said main lines II and H3respectively to a binding post I 40 and thence through a conductor I45to the other member I42 of the trouble switch. l

Said local shunt circuits pass through pull stations I08, I89, I I0 andFigs. 9 to 12 normally short circuit the magnets 80, 8| respectively,whereby if a break occurs in either local circuit one of the magnetswill become not shunted, but will be energized and a trouble signal willbe sent.

Means I5 I, I 53 carried by the transmitter cover serves for momentarilyopening said trouble switch I42, M2 during closing movement of thecover, thereby to cause the energizing of bothmagnets 80, 8! and thesending of an alarm signal should the break in the shunt circuit be notrepaired.

A pair of manually operated switches I3I. I3I, I32, I34 (Figs. 1 and 9to 12) in each pull box box inserted in both circuits respectively areoperated by a single lever to break both shunts. thereby to magnetizeboth magnets and send an alarm signal, said switches being constructed.to ground both shunt circuits, one at a time only, thereby to energizesaid magnets 88, 3! through one circuit or the other if one of the mainlines it! or H be broken, thereby to send an alarm signal.

A cut-out switch means III, H2, H3, III, I I2, I I3 (Figs. 1 and 2operated by the transmit ter whenever the signal wheel rotates, servesto cut-out the double shunt circuit completely while the signal is beingsent and to cause a direct shunt 194, III, H3, H4, H3. III. 04connecting the main lines in series with the signal switch. thus toprevent the interference with any signals being transmitted by the tripbox after a pull station has been once operated.

Now the various parts of the system will be described in detail.

The transmitter or trip boat:

The signal transmitter 25 (Figs. 3 to 8) comprises a clockwork 28 (Fig.4) having springs 29, a winding arbor 30, a toothed signal or breakwheel 3I thereon having two sets 32 of signal teeth. and an escapement33 including an oscillatory escapement arbor 34 carrying fast thereon anoscillatory disk 35 carrying an engagement pin 36.

The detent mechanism A pair of horizontally alined fulcrum blocks 38(Fig. 6) fast on the inner face of the rear pillar plate 39 carry aninverted cross-shaped detent lever 40, 4I having horizontal members 42journaled at their ends between said blocks 38, and a substantiallyvertical portion 40, 4! forming a short downwardly extended roundedengagement arm 4i and a long upper detent arm 40 provided with a detentpin 43 adapted to engage said engagement pin J5 when. the detent arm isrocked frontwardly and said engagement arm M is rocked rearwardly.

A pin 45 (Fig. 5) projecting rearwardly from said detent arm into a holein the pillar plate is surrounded by a weak spring 48 compressed betweenthe pillar plate and detent arm to move the detent arm and pinfrontwardly for stopping the clockwork.

An actuating member 48, 49 (Figs. 6 and '7) comprises a radial arm 48fast on the winding arbor, andan arcuate rim 49 about 185 degrees inlength co-axial with the arbor and engageable with said engagement armII to hold the detent pin 43 rearward in releasing position and providedin its front face with a winding signal notch 50 and a trouble signalnotch 5| both remote from the end of the rim and adapted to receive theengagement arm 4| to permit the detent-pin 43 to move under the'actionof the weak spring to detent position.

Pins 53, 54 fast on the pillar plate and engageable by the radial armlimit the winding and unwinding movement of the engagement piece andwinding arbor to about 180 degrees and serve to prevent the rim fromdisengaging the engagement arm at either end of the rim.

The winding signal notch 50 is spaced a sufficient distance from theengagement arm 4| when the clockwork is wound up, to cause the detentpin to be held disengaged until the signal wheel makes a half turn andsends one winding signal to indicate to the central oflice that thetransmitter has been wound up.

The tripping levers A horizontally elongated wire loop 51 fast on theupper end of the detent arm 48 has curved engagement end portions 58;and a pair of short spindles 59 journaled in the rear pillar plate belowsaid portions respectively carry fast thereon normally raised trippinglevers 69, 6! adapted to pivot downwardly toward each other to theposition of Fig. 5, and each provided with a tripping cam 63 adapted tobe disposed outside of and to clear the loop 51, as at the left of Fig.6 when the lever is in upright position and when the lever movesdownwardly to engage the front face of one of said engagement portions58, force back the loop and detent pin and pass inwardly of theengagement portion, and to clear the engagement portion after thetripping lever has moved to its lowest position of movement, thereby tomomentarily release the detent pin from the engagement pin to permit thenotch to move away from said engagement arm so that an unnotched portionof the rim 49 will cause the detent to move back.

Springs 65 (Fig. 5) mounted on the rear of the pillar plate respectivelyengage downwardly pointed radial arms 66 on each of said spindles foryieldably moving inward the upper ends of the tripping levers, themovement of the springs being limited by plate members 61, gravitycompletely lowering the tripping levers.

Each tripping cam 63 has an outer slanting cam face 69 (Fig. 8) to campast the engagement portion 58 when the tripping lever is reset, and aninner slanting cam face 10 to engage the engagement portion 58, when thetripping lever falls, to release the detent, and an inner abrupt face TIto engage the outer face of the engagement portion to hold the camagainst further inward movement until the notch 50 or 5! of the arcuateportion has time to move away from the engagement arm to cause theunnotched portion of the arcuate member to hold back the loop then topermit the tripping cam to pass inward.

The tripping magnets A horizontally disposed plate M (Fig. 3) pivotedabove each tripping lever carries an armature 15 and a downwardlyprojecting retaining pin 16 engaging a projection 1! or each trippinglever to hold the lever upright when the armature is lowered; and anelectro-magnet 80, 8! over each armature is adapted when energized toraise the associated armature and release the tripping lever. Behind themagnets 80, 8| are similar magnets as indicated diagrammatically in Fig.2, but hereinafter each magnet and the one behind it will be consideredas one magnet.

Said tripping levers respectively have on the upper end thereof, innerextensions 82, 83 (Figs. 5 and 6) adapted to occupy a common space wheneither tripping lever is lowered to its lowest position and when in saidspace to prevent the entrance thereto of the other extension, thus tohold the other tripping lever in an intermediate position nearly as lowas its lowest position, each tripping cam having thereon a projection 85adapted to pass the engagement portion 58 of the loop when the campasses to its lowest position, but adapted, when its tripping lever isin said intermediate position, to engage the engagement portion 58 andhold the detent pin 43 disengaged whereby when both magnets have beenenergized and both tripping levers lowered, as in Fig. 5, thetransmitter will run down completely.

Tripper-lever resetting means A short shaft 86 (Fig. 5) projectingthrough the rear pillar plate 39 carries fast thereon an intermediatelyfulcrumed lever 8'1 disposed against the inner face of the pillar plateand provided under the fulcrum point with a downward projection 88 andhaving its arms slightly upturned and engaged under rollers 89 inwardlyeccentrically mounted on the tripping levers respectively.

The actuating member rim 49 (Figs. 6 and '7) has a cam projection 98 onits peripheral face engageable with said downward projection 88 to movethe downward projection 88 in one direction as the transmitter is nearlyrundown, thereby to raise one upturned end and associated roller 89 andtripping lever GI, and engageable with said downward projection to moveit in the opposite direction and raise the other tripping lever 69 asthe rewinding is starting.

A downwardly and frontwardly extending arm 9| fast on the rear part ofsaid short shaft 86 is engaged by a pair of vertical springs 92 havingtheir lower ends mounted on the pillar plate and their upper endspressing upon opposite sides of said short shaft and. said arm 9!, toyieldably press the lever 87 to mid-position, the shaft limiting theinward movement of the springs.

Operation of the transmitter clockwork If after the winding signal,while the arm M is still received in the notch 50, a break develops inone of the local circuits I55, 36, H3? or I05, I06, I61, one of theelectromagnets 80 or 8! will become not shunted and energized, thusraising an armature l5 permitting to fall one of the levers B8 or 6|.If, for instance, the lever 6! falls, the face 10 (Fig. 8) of thetripping cam 63 engages the loop portion 58 and forces back the detentlever 48 and pin 43 against the action of the spring 6, until theengagement portion 58 rests against the abrupt face H, thus preventingthe further fall of the tripping lever El and holding the detent pin 43disengaged until notch 59 moves from the arm 4! and the unnotchedportion of the rim 49 engages the arm 4! and pushes the arm 8| furtherforward and the arm 45 further back, to cause the portion 58 to clearthe face N (Fig. 8)- and let the trip lever drop to the lowest position.

When the unnotched portion of the rim 49 is thus engaged, it holds thedetent pin 43 in releasing position until the next notch 5i receives thearm 4!, thus permitting the pin 43 to stop the escapemcnt after onetrouble signal has been sent.

When the transmitter is rundown, the actuating member 48, 49 is in theposition indicated by the dotted lines 48 (Fig. 6). In winding upcompletely, the operator applies the key and turns the winding arboruntil the arm 48 takes the position 48" with one end 49 (Fig. 7) of therim 29 close to the arm M. The operator then releases the key and themember 49 moves 30 degrees to the position of Fig. 7, thus rotating thesignal wheel a half turn, thus sending one signal, which is interpretedat the central ofiice as a winding signal, showing that the transmitterwas completely wound up.

When the end .8 is adjacent to the arm ii, the unnotched portion of therim 49 holds the arm ll frontward and holds the detent pin 42 disengagedfrom the pin 36, and the transmitter runs until the arm ll is receivedin the notch 58 permitting the spring 46 to cause the detent pin 62 tostop the escapement, thus sending the one winding signal.

If no trouble signal is sent and a pull station lever is pulled nextafter the winding signal while the arm H is in the not-ch 58, both shuntcircuits will be broken, both magnets will be energized, and both triplevers will fall. It is not practically possible that both levers shouldreach the lowest limit at the same instant, and one lever,

for instance the lever 68, will reach the lower limit first, and theextension 82 of the lever 51 will later rest on the extension 83 of thelever 66 and hold the projection 34 (Fig. 8) in engagement with theadjacent loop portion 58 and hold back the detent arm All and preventthe entrance of the arm 4| into the recess 5! as the latter moves to thearm 4|, thus preventing the stopping of the clockwork until the latteris completely run down and a long alarm signal is sent.

If after a trouble signal and the lowering of one trip lever, caused bythe energization of one magnet, the other or both magnets be energized,the trip levers will take a position, for instance as in Fig. 5, and thetransmitter will rundown completely and send a long alarm, one signalless in number than if a trouble signal had not been sent.

The usual ratchet 94 (Fig. '7) fast on the wind ing arbor is engaged bya pawl 95 on the main drive wheel 96. The teeth of the ratchet are sixtydegrees apart and the signal wheel gives two complete signals when thewinding arbor unwinds the angle between adjacent ratchet teeth. If thearbor be wound up less than one tooth the pawl will not catch on a newtooth and no signal will be sound-ed. If the arbor is wound up as muchas one tooth and less than two teeth, two signals will be soundedshowing the ofhce that the transmitter was not completely wound up. Ifthe arbor be wound up as much as the distance of two teeth, theengagement arm GI will be received in the trouble notch; no signal willbe sent, and the main oflice will want to know why. If the arbor bewound up more than two and less than three teeth, no ratchet will engagethe pawl. and the winding arbor will move freely back to the troublenotch position and no signal will be sounded. Only when the arbor iswound the distance of three full teeth can one signal as distiguishedfrom two signals be sent, thus indicating positively that thetransmitter is fully wound. If the winding up signal has been given, asecond rewinding will not cause the pawl to be engaged and no furthersignal will be then given.

From the above, it will be seen that after an alarm, the only waypossible to send a winding signal (a single signal) is to completelywind the arbor.

The signaZ switch Associated with the signal wheel 3I is a normallyclosed signal switch I06, Itll, I02 (Fig. 2) comprising a pair of springcontacts IElil, IllI respectively connected to the main line wire II anda conductor I03 connected to the magnet 89. A spring contact pen I02normally engages said contacts to close the main line circuit, and isengageable with the grounded signal wheel 3| to break the main linecircuit in normal signalling or to connect the main line wires throughthe frame or a conductor I69 to the ground for signalling through theground and either one of the main line wires if the other main line wireshould be broken.

The pair of pairs of releasing electro-magnets 80, SI are interposed inseries between the lines 58 and II substantially near the normallyclosed signal switch, whereby said magnets whenever the current is notshunted around them, will be energized by the line current to rase thearmatures E to permit signalling, and whereby when the magnets areshunted or short circuited the magnets will not be energized, armatures15 will not be lifted and no signal will be sent.

The pull-station cut-out The signal initiating system for shortcrcuiting the one or more magnets comprise a normally closed doubleshunt circuit H13, I04, I95, I05, E91 and E84, I95, I06, I01 (Figs. 1and 2) normally connecting the magnets and signal switch, a plurality ofgrounding pull stations I83, I99, IIO interposed in said shunt circuits,and a cut-out switch mechanism III,II2,II3,III,II2,II3' operative duringsignal transmittingfor maintaining the magnets short circuited andcompletely cutting out the shunt circuit to prevent interference by theground of the stations with the signal transmission.

Each cut-out mechanism comprises shunt springs forming a double throwout out switch comprising intermediate spring contact members IIi, IIIconnected by conductors I85, I84 respectively to the ends of the mainlines II and I8 adjacent to the magnets.

Said intermediate members I I I, II I respectively normally engagespring shunt contact members I I2, I I2'connectedtoopposite ends I05,I05'of said local line respectively, whereby the local line normallyshunts the current around the magnets 80, 81 and leaves themde-energized and the armatures down.

Short circuiting spring contact members II 3, H3 are electricallyconnected to each other by a conductor H4 and have their contact endsoperatively associated to each other by an insulating block II 5 and arenormally disengaged from said intermediate members III, III.

An insulating shunt-cut out disk cam II1 fast on the signal arbor isprovided with a pair of diametrically opposite recesses H8, and isengageable by the short circuiting member- 3' formed as a pen normallyengaging in one of said cam recesses II8 while the signal wheel isdisengaged and while the transmitter is normally stationary, and adaptedto be engaged by the periphery of the cam II! when rotating, and whenthe signal is being transmitted, to move the ends of the shortcircuiting members II3, I I3 and cause them to engage the intermediatemembers II I, II I to electrically shunt the line around the magnets andto push the interme-.

diate members from the normally engaged shunt members H2, H2, thereby tocut out the local double shunt circuit completely while the signal isbeing sent to prevent possible interference of the grounds with thesignal.

The pull boxes Each pull station comprises a main housing I20 (Fig. 14)including a front wall I2I hinged at I22 thereto and formed with a frontcompartment I23 (Fig. 13) having a door I24.

A pull lever shaft I25 passing through the wall I2I carries a pull leverI26 fast on its front end and a cam I21 fast on its rear end, suitablewell known means (not shown) normally yieldably raising the lever andlimiting the movement of the lever and cam.

Pull station switches An insulating bracket I29 (Fig. 9) on the innerface of the wall I 2! below the cam I21 carries a pair of jacksrespectively comprising normally engaged inner contact springs I30, I30and camcngaging intermediate active springs I3I, I3I' having normallyinter-engaging contacts thereon and forming a normally closedlocal-shunt-line I switch, and also outer grounded springs !32, I32adapted to be contacted by the active spring respectively when thelatter are forced outwardly.

Each active spring I3I, I3I has its outer end portion I33, I33 curved toform an engagement portion engageable with the cam I21.

Said cam I21 has diametrically opposite normally engaged portions I35, I35 of small radius adapted to receive the engagement portions I33, I33to let the active springs touch both inner springs respectively when thelever is in normal raised position as in Fig. 9.

As the lever is moved downward, the portions I33, 133 are engaged by apair of diametrically opposite circuit breaking inclined portions I36,I36 respectively, as in Fig. 10, for simultaneously breaking bothcircuits as the lever is lowered, thus to break both shunt circuits I05,I05, I66, I06, I01, I01.

Diametrically opposite land portions I31, I31

(Fig. 11) respectively of intermediate and maximum radius, adjacent tosaid inclined portions engage said engagement portions I33, I33respectively as the lever is further lowered, one of said land portionsI31 having a radius sufiicient to hold open the associated local switchI30, I3I and to cause one active spring I3I to engage the associatedgrounded spring I32, the other land portion I31 having a radius onlysuificient to open the adjacent local switch without causing the activespring to engage the associated grounded spring I32, as in Fig. 11.

Final portions I38, I38 respectively engage the active springs when thelever is in final down position and have radius respectively equal tobut reversed to that of the land portions I31, I31 for causing the otheractive spring I3I to be grounded leaving the switch I30, I3I open as inFig. 12.

The double shunt circuit The double shunt circuit comprises anintermediate binding post I40 (Figs. 1 and 2) connected by the pair ofshunt circuits to said main lines respectively.

Said shunt circuits comprise conductors I05, I05 respectively connectingsaid shunt contact members II2, H2 to active springs I3I, I3Irespectively of the pull station I08, conductors I 06, I06 respectivelyconnecting the normally engaged inner contact springs I30, I30 of saidstations except the last station I II! to the respective active springsI3I, I3I of the next station I00, H0, and conductors I01, I01 connectingthe normally engaged contact springs I30, I30 of the last station withsaid binding post I40.

The testing switch A normally closed testing switch I4 I, I42 (Figs. 1and 3) mounted on the inner face of the top wall I43 of the transmitterhousing I44 comprises normally interengaged upper and lower insulatedcontact springs I4I, I42 mounted on said face, the lower spring I 52having a projecting end I45 projected beyond the upper spring and havinga frontwardly and downwardly inclined lip I46.

Conductors I48, I49 respectively connect said upper and lower springsI4I, I42 to the part I50 of the main circuit between said magnets andsaid binding post I40.

An insulated blade I5I mounted on the cover I52 of the transmitterhousing has a free-end lug I53 adapted, during door-closing movement, tocam over said projecting end I45 and to momentarily open the switch, andto cam under said end I05, without opening the switch, duringdooropening movement.

Operation of the system Under normal conditions, the system is on aclosed unbroken main line circuit and the current fiOWS through theshunt circuit I05, I06, I01, I05, I06, I01, short circuiting themagnets, which are thus deenergized.

When the clockwork is rewound, both trip levers are automaticallyraised, a winding signal is sent, leaving the member 43, 49 in theposition of Fig. 7.

If an alarm is to be sent, the pull lever I 26 (Fig. 13) is lowered,thus breaking both shunt circuits at the springs I30, I3I and I30, I3I,as at the switch I08 (Figs. 1 and 10), thus causing both magnets to beenergized and both trip levers to fall, sending a long alarm.

If a break should occur in, either shunt circuit, for instance in theconductor I05 (Fig. 1), no

current could flow through the shunt circuit I05, I06, I01, I40, I49,I42, I4I, I48, I50 and the magnet 80 would be not short circuited andwould be energized, the trip lever 6 I would fall and a trouble signalwould be sent, leaving the other trip lever 50 raised and the arm M(Fig. '1) received in the notch 5 I.

If after this break and trouble signal, the break be not yet repaired,an alarm may still be sent in the usual way, by pulling the lever I26,causing the switch I30, I3I' to open, breaking the shunt circuits I05,I06, I01, I49, I48 around the magnet 8 I, thus dropping the remainingtrip lever and sending an alarm.

If after the break in the shunt circuit and the consequent troublesignal, the break be not repaired, the subsequent winding of thetransmitter will send a Winding signal and trouble signal, then thesubsequent closing of the transmitter cover, will open the troubleswitches I4I, I42 and cause the conductors I40, I49 to be removed fromthe double shunt circuit, whereupon the two shunt circuits form a singleshunt circuit I04, I05, I06, I01, I01, I08, I05, I04. If a singleelement of this circuit be broken, the magnets are no longer shunted andboth become energized on the opening of the switch I4 I, I42, thuscausing the transmitter to run down on closing the transmitter cover,thus calling further attention to the fact that the break still exists.

If there should develop a break in one of the main line wires I or I I,the switch 2| (Fig. 1) would be moved to the position of the dottedlines, sending current of the same sign into both ends of the main line,to cause signal current to pass through the contact member I00 or IOI,the pen I02, the signal wheel 3|, the frame or conductor I60 to theground.

Under such circumstances the transmitter is normally on open circuit andcurrent must be led through the magnets if an alarm is to be sent. If,for instance, the break is in the line I I between the transmitter andthe central oifice, the partial lowering of the lever, breaks the shuntcircuits as at the dotted lines station I08 and at a later instantcloses the contact between springs I3 I I32 as shown by the dotted linesat station I09, thus connecting the line II to the pull box frame orconductor I6I to the ground. This, however, does not energize themagnets, as the current would take the short circuit through I04, I,E06. When, however, further movement of the lever I20 causes contactbetween the springs I3I, I32 as at the dotted line in station H0, andcurrent will pass through line I0, magnets BI, 80,

conductors I04, I05, I06, springs I3I, I32 of station IIO, conductor ISIto the ground, thus energizing both magnets and sending an alarm.

If the break is in line wire I0, pulling of the lever causes current inwire II, the magnets, conductors I04, I05, I00, springs I3I, I32, andthe ground.

If in either of the above cases, the operator should hold the lever I26in position to close the switch I3I, I32 or I3I, I32, the operation ofthe cam II'I (Figs. 2 and 3), would open switches III, H2 and III, II2(Fig.1 and close switches III, I I3 and III, I I3, shunting the doubleshunt current through the direct shunt II4 during the actual sending ofthe signal, so that the signal current could never be led off throughthe grounds I BI or IE I instead of through the grounded signal wheel.

I claim as my invention:

1. In combination, a pair of main line wires; a

transmitter interposed therebetween including a normally shuntedelectromagnet, a grounded signal wheel, a switch in one main line wireoperable by the wheel, said transmitter including means whereby a signalis sent if the magnet is ene gized; a plurality of pull stations; alocal shunt circuit short circuiting the magnet; and a switch assemblyin each pull station having grounded members operable to break the shuntand to apply the grounded members respectively to points of the shunt onboth sides of the break.

2. In combination, a pair of main line wires; a transmitter interposedtherebetween including normally shunted electromagnets and means wherebya signal is sent, through the wires or one wire and the ground, if amagnet is energized; a plurality of stations; circuits short circuitingthe magnets respectively; and a switch in each station operable to breaksaid circuits, and ground the circuits respectively at different times.

3. In combination, a transmitter operative through a ground; a pluralityof stations; a pair of local lines connecting the stations andtransmitter; means in the stations for breaking both lines; means forcausing the transmitter to signal if one of said lines break; means forcausing another signal if the other line is broken; means for groundingboth of said lines; and means for causing a signal if one of said linesis grounded.

4. In combination, a transmitter operative through a ground; a pluralityof stations; 2. line connecting the stations to the transmitter; meansin the stations for breaking the line; means for causing the transmitterto signal if said line breaks; means in the stations for applying aground to said line when broken; means for causing a signal if said lineis grounded; and means for separating the grounded portion of the linefrom the transmitter during signalling.

5. In combination, a pair of main line wires; a transmitter interposedtherebetween including a. normally shunted electromagnet and groundedmeans whereby a signal is sent in part through the ground if the magnetis energized; a plurality of stations; a shunt short circuiting themagnet; a switch in each station operable to break the shunt and groundboth sides of the break; and means operable to short circuit thegrounded shunt during signal sending.

6. In combination, a pair 01 main line wires; a transmitter including anelectromagnet connected between said lines and means whereby a signal issent when the magnet is energized; a plurality of stations; a shuntcircuit shunting said magnet and passing through the stations; a switchin each station operable to break the shunt; and means operable by saidtransmitter to disconnect both ends of the shunt circuit from the magnetduring transmitting.

7. In combination a transmitter; a circuit controlling the transmitter;a casing for the transmitter having a door; a testing means for saidcircuit; and means for operating the testing means when door isoperated.

8. A system comprising a pair of main line wires; a transmitterincluding an electromagnet interposed between said main line wires andmeans whereby a signal is sent when the magnet is energized; a localshunt circuit connecting the main lines; a normally closed local stationswitch adapted when operated to break the shunt; and 2. normally closedtrouble switch connected in series in said shunt circuit for.causing thetransmitter to give a signal when the trouble switch is opened and theshunt is broken; a casing for the transmitter having a door; and meansfor momentarily opening said trouble switch when the door is closed.

9. In combination a pair of main line wires; a transmitter including anelectromagnet interposed between said main line wires and means wherebya signal is sent when the magnet is energized; a normally closed troubleswitch having one member connected to one line wire near said magnet; aplurality of stations; a local shunt circuit connecting the main linesto the other member of the trouble switch and passing through the pullstations, thereby short circuiting the magnet; a switch in each stationadapted when operated to break the shunt; and means including a magnetshunted by said trouble switch when closed, for causing the transmitterto give an additional signal when said last named magnet is energized.

10. In combination, a pair of main line wires; a transmitter including asignal wheel switch in one main line wire and electromagnets connected,in series between said lines to form a signal circuit; said transmitterincluding means whereby one signal is sent if either magnet only isenergized and a long signal is sent when both are energized; pullstations; a pair of local shunt circuits connecting said main linesrespectively to the signal circuit between said magnets and passingthrough the pull stations; a switch assembly in each station operable tobreak both shunts; and means operated by the transmitter to cut out saidlocal circuits and direct shunt the magnets until a complete signal istransmitted.

11. In combination, a pair of main wires; receiver means connectedthereto and adaptable for closed circuit operation or grounded opencircuit operation; a transmitter including a normally closed signalswitch in one line wire, a grounded signal wheel normally out of contactwith the switch, electromagnets interposed in series be tween said mainline wires to form a signal circuit; means whereby one signal is sent ifeither magnet only is energized and a longer signal is sent when bothare energized; pull stations; a pair of local shunt circuits connectingsaid main lines respectively to the part of the main circuit betweensaid magnets and passing through the pull stations; a switch assembly ineach pull station adapted when operated to break both shunts and toground both shunt circuits, one at a time; and cut-out means operated bythe transmitter when the signal wheel rotates, to cut-out the shuntcircuits and to direct shunt the magnets.

12. In combination, a pair of main wires; receiver means connectedthereto and adaptable for closed circuit operation or grounded opencircuit operation; a transmitter including a normally closed signalswitch in one line wire, a grounded signal wheel normally out of contactwith the switch, electromagnets interposed in series between said mainline wires to form a signal circuit, means whereby a short signal issent if either magnet only is energized and an additional signal is sentwhen both magnets have been energized; a normally closed trouble switchhaving one member connected to the main circuit between said magnets; aplurality of stations; a pair of local shunt circuits connecting saidmain lines respectively to the other member of the trouble switch andpassing through the pull stations; and a switch assembly in each pullstation adapted when operated to break both shunts and to ground bothshunt circuits.

13. In combination, a source of current having a grounded and anungrounded terminal; a pair of main lines wires extending respectivelyfrom said terminals; means for connecting bot-h wires to the ungroundedterminal only; receiving means operated by impulses in said wires; atransmitter including a pair of normally deenergized electromagnetshaving their coils in series between said wires; a normally closed codeswitch in one wire; means set in operation by the transmitter wheneither electromagnet only is energized to intermittently ground and openthe switch to send one signal, and to send an additional signal whenboth magnets are energized; local stations; loops passing from therespective lines through said stations to the conductor between saidmagnets, thereby shunting and deenergizing the coils; a unitary movablemanual operating means at each station; means operated by a singlestroke of the operating means for successively breaking the loops andthen successively grounding only that portion of the loops connected tothe lines: and means operated by the transmitter for disconnecting theloops from transmitter only during transmitting.

14. In combination, a source of current having a grounded and anungrounded terminal; a pair of main line wires extending respectivelyfrom said terminals; means for connecting both wires to the ungroundedterminal only; receiving means operated by impulses in said wires; atransmitter including a pair of normally deenergized electromagnetshaving their coils in series between said wires; a normally closed codeswitch in one wire; means set in operation by the transmitter wheneither 'electromagnet only is energized to intermittently ground andopen the switch to send one signal, and to send an additional signalwhen both magnets are energized; local stations; a conductor connectedbetween said coils; loops passing from the respective lines through saidstations to said conductor thereby shunting and deenergizing the coils;means for breaking the loops and then successively grounding only theportion of the loops connected to the lines; and means operated by thetransmitter when transmitting for shunting said coils and disconnectingthe loops from transmitter only during transmitting.

15. In combination, a source of current having a grounded and anungrounded terminal; a pair of main line wires extending respectivelyfrom said terminals; means for connecting both wires to the ungroundedterminal only; receiving means operated by impulses in said wires; atransmitter including a pair of normally deenergized electromagnetshaving their coils in series between said wires; a normally closed codeswitch in one wire; means set in operation by the transmitter wheneither electromagnet only is energized to intermittently ground and openthe switch to send one signal, and to send an additional signal whenboth magnets are energized; local stations; a door for the transmitter;a normally closed trouble switch having one element connected betweensaid coils; means operated by the door for opening the trouble switchwhenever the door moves closed; loops passing from the respective linesthrough said stations to the other element of said switch, therebyshunting and deenergizing the coils; manual operating means and meansoperated by the operating means for breaking the loops and thensuccessively grounding only the portion of the loops connected to thelines; and

means operated by the transmitter for shunting said coils anddisconnecting the loops from transmitter only during transmitting.

16. In combination, a pair of main line wires; a transmitter interposedtherebetween including adjacent electromagnets and a signal wheel switchconnected in series between the main line wires; said transmitterincluding means whereby one signal is sent if one magnet is energizedand an additional signal is sent when both magnets have been energized;a pair of local shunt lines connected to said main lines respectivelyadjacent to said magnets; normally closed local-station switches in saidshunt lines; and means normally connecting the outer end portions ofsaid shunt lines to a point in the main circuit between said magnets andoperable to disconnect said outer end portions from said point whileholding said outer ends connected to each other.

1". In combination, a pair of main line wires; a transmitter interposedtherebetween including adjacent electromagnets and a signal wheel switchconnected in series between the main line wires; said transmitterincluding means whereby one signal is sent if one magnet is energizedand an additional signal is sent when both magnets have been energized;a pair of local shunt lines connected to said main lines respectivelyadjacent to said magnets; normally closed local-station switches in saidshunt lines; and means normally connecting the outer end portions ofsaid shunt lines to each other and to a point in the main circuitbetween said magnets, said means being operable to disconnect said outerend portions from said point while said outer ends are still connectedto each other.

18. In combination, a source of current having a grounded and anungrounded terminal; a pair of main line wires extending respectivelyfrom said terminals; means for connecting both wires 1;

to the ungrounded terminal only; receiving means operated by impulses insaid wires; a transmitter including a pair of normally deenergizedelectromagnets interposed in series between adjacent end portions of thewires, a transfer switch associated with each wire, each having anormally engaged contact, a normally disengaged contact, and a transferelement connected to the end of the associated wire; a normally closedcode switch in one wire between the receiving means and the magnets;means set in operation by the transmitter when either electromagnet onlyis energized to intermittently ground and open the switch to send onesignal, and to send an additional signal when both magnets areenergized; a conductor connected between said coils; local stations;loops passing from the respective normally engaged contacts through saidstations to said conductor thereby shunting and deenergizing the coils;means for breaking the l ops and then successiveiy grounding only theportions of the loops connected during the break to the normally engagedcontacts; a conductor in the transmitter connecting said normallydisengaged contacts; and means operated by the transmitter fortransferring said transfer elements to the normally disengaged contactsfor shunting said coils and disconnecting the loops from the transferelement only during transmitting.

RICHARD M. HOPKINS.

